Magnesiosilicates

ABSTRACT

Novel magnesiosilicate compounds for use in detergent compositions and as water softeners have a calcium binding capacity of at least 10 mg CaO per gram, a magnesium binding capacity of at least 10 mg MgO per gram and a calcium binding rate of no more than 300 seconds, all at room temperature. The compounds have a stuffed silica polymorph-related structure or a layered structure with a broad X-ray powder diffraction peak at a d-spacing of between 11 and 17 Å. The compounds have an anhydrous composition M a  Mg b  Al c  Si 1- (b+c) O d , where M--alkali, 0.0&lt;a&lt;2.0, 0.0&lt;b&lt;0.7, 0.0≦c≦0.3, 1.15&lt;d&lt;3.0, c&lt;b, and partial substitution of M, Mg, Al and Si is permitted. The compounds are prepared by solid state reaction or aqueous reaction of starting material such as magnesiosilicate mineral with alkali oxide-containing reagent under relatively mild conditions or by treating a magnesiosilicate compound having a stuffed silica polymorph-related structure with aqueous solution.

TECHNICAL FIELD

This invention relates to magnesiosilicate compounds and is particularlyconcerned with such compounds which can be used as water softeners ordetergent builders. The magnesiosilicate compounds may have other uses,including, for example, separating heavy metals and other contaminants.

BACKGROUND ART

In recent years there has been a trend towards low-phosphate andphosphate-free detergent formulations. To this end a number ofnon-phosphate detergent builders and water softeners have beendeveloped. Na zeolite A, a synthetic aluminosilicate of compositionNaAlSiO₄, has been used in high volumes for many years and is aseffective as sodium tripolyphosphate (STPP) at removing calcium but notas effective at removing magnesium. This aluminosilicate zeolite hasrecently been joined by zeolite P (European Patent Applications 0 384070 and 0 565 364) as a commercially used builder which shows enhancedexchange kinetics. Alternative technologies are based on solublesilicates (amorphous and crystalline) which soften water effectively andgenerally show better magnesium removal than Na zeolite A. A crystallinelayered sodium silicate SKS-6 (Na₂ Si₂ O₅), which is used commercially,has also been developed by Hoechst AG and is described in U.S. Pat. Nos.4,664,839, 4,820,439, 4,950,310 and 5,308,596. Also, crystalline sodiumsilicates with the kanemite structure and composition NaHSi₂ O₅.xH₂ Ohave recently been developed by Hoechst AG, as described in EuropeanPatent Application 0 627 383.

Synthetic alkali magnesiosilicates having an anhydrous composition ofxM₂ O.ySiO₂.zM'O where M represents Na and/or K; M' represents Ca and/orMg; y/x is 1.4 to 2.1; z/x is 0.001 to 1.0; K/Na in M₂ O is 0 to 80; andMg/Ca in M'O is 0 to 100 have recently been proposed by Kao Corporationin European Patent Application 0 630 855. These materials, which have achain silicate structure as described in European Patent Application 0550 048, are shown to have high calcium binding capacity and to haveutility as water softeners and as alkali adjusting agents. In addition,they are described as particularly useful for their good moistureresistance (Japanese Patent Application Kokai 07,330,325).

Synthetic alkali magnesiosilicate compounds with the general formulaM_(2-2x) Mg_(1-x) Si_(1+x) O₄, where M is an alkali metal, have beenreported previously, as discussed below. However, these highlycrystalline compounds have not been recognised as having properties thatenable them to be used as water softeners or detergent builders.

The compounds Na₂ MgSiO₄ (R. D. Shannon, Phys. Chem. Miner. 4, 139-148,1979), Na₄ Mg₂ Si₃ O₁₀ (C. M. Foris et al. J. Appl. Cryst. 12, 405-406,1979) and K₂ MgSiO₄ (E. W. Roedder, Am. J. Sci., 249, 224248, 1951; A.S. Berezhnoi et al. Izvestiya Akademiii Nauk SSSR, NeorganicheskieMaterialy 12, 1653-1658, 1976) have all been described as havingstructures closely related to that of the silica polymorph, cristobalite(see FIG. 1). It has also been proposed (E. W. Roedder, Am. J. Sci.,249, 224-248, 1951) that in terms of the general formula M_(2-2x)Mg_(1-x) Si_(1+x) O₄, when M=K and x=0.5, i.e. KMg₀.5 Si₁.5 O₄, acompound is formed which has a structure closely related to that of thesilica polymorph, tridymite (see FIG. 2).

Tridymite and cristobalite both have the composition SiO₂ and comprise a3-dimensional framework of corner-connected SiO₄ tetrahedra. They areclassified as framework silicates or tectosilicates.

By analogy with alkali aluminosilicate analogues, the cristobalite- andtridymite-related compounds described above can also be described asstuffed derivatives of the cristobalite and tridymite structures (M. J.Buerger, American Mineralogist 39 600-614, 1954), and therefore asstuffed silica polymorph-related structures, in that up to half of thesilicon cations in the silicate framework in each case are replaced bymagnesium cations. Alkali cations, which are required for charge balance(Si⁴⁺ <-->Mg²⁺ +2M⁺, M=alkali) occupy the interstices in the respectiveframeworks (see FIGS. 1 and 2)--hence the descriptions "stuffedcristobalite" and "stuffed tridymite". Other stuffed silicapolymorph-related structures include "stuffed quartz".

All of the above alkali magnesiosilicate compounds having stuffed silicapolymorph-related structures were prepared from synthetic reagents andunder reaction conditions that promoted the formation of very wellcrystallised and ordered materials.

SUMMARY OF THE INVENTION

We have now discovered that some forms of magnesiosilicate compounds notpreviously described, including some having a stuffed silicapolymorph-related structure, can have advantageous water softening anddetergency building properties, as measured in terms of a combination oftheir calcium binding capacities, their magnesium binding properties andtheir calcium binding rates. The aforementioned known magnesiosilicatestructures having a stuffed silica polymorph-related structure may havehad some but not all of these properties.

According to the present invention there is provided a magnesiosilicatecompound having a calcium binding capacity (CBC) of at least 10 mg CaOper gram at room temperature, a magnesium binding capacity (MBC) of atleast mg MgO per gram at room temperature. and a calcium binding rate(CBR) of no more than 300 seconds at room temperature, being the timetaken to remove half of the Ca²⁺ from a ˜100 ppm Ca²⁺ solution at aloading of 3 g per liter, and having either a stuffed silicapolymorph-related structure or a layered structure with a characteristicbroad X-ray powder diffraction peak occurring at a d-spacing of between11 and 17 Å. Central to the present invention is the discovery that somestuffed silica polymorph-related magnesiosilicates, particularly thosethat are imperfectly crystallised and possess substantial disordering ofthe framework cations, and magnesiosilicates having a layered structurewith a characteristic broad X-ray powder diffraction peak occurring at ad-spacing of between 11 and 17 Å, preferably between 12 and 16 Å, canhave a significant calcium binding capacity (CBC). magnesium bindingcapacity (MBC) and a relatively high calcium binding rate (CBR) inaqueous solution. For the purposes of the present invention CBC isexpressed in units of mg CaO per gram of anhydrous magnesiosilicate andMBC is expressed in units of mg MgO per gram of anhydrousmagnesiosilicate, both at room temperature. Advantageously, thecompounds of the invention may have a CBC of at least 20, preferably atleast 50 and in many embodiments at least 100. Advantageously, thecompounds of the invention may have an MBC of at least 15, preferably atleast 40 and in many embodiments at least 90. When well-prepared, thesenew compounds may have a CBC of at least 150 and/or an MBC of at least140. For the purposes of the present invention, CBR is expressed interms of the time taken to remove half of the Ca²⁺ from a ˜100 ppm Ca²⁺solution at room temperature at a loading of3 g per liter.Advantageously, compounds of the invention may have a CBR of no morethan 200 seconds, preferably no more than 100 seconds, more preferablyno more than 50 seconds, even more preferably no more than seconds, andmost preferably no more than 10 seconds.

The compounds of the invention advantageously also have an oilabsorption (OA) of at least 50 g oil per 100 g of anhydrous material,preferably at least 70 g oil, more preferably at least 100 g oil per 100g of anhydrous material.

Methods for determining CBC, MBC, CBR and OA are described hereinafter.

The magnesiosilicate compounds of the invention may be characterised interms of their composition, which may, in anhydrous form of thecompounds, be given by M_(a) Mg_(b) Al_(c) Si₁₋(b+c) O_(d), whereM=alkali, optionally partially substituted by H or NH₄ ; where0.0<a<2.0, 0.0<b<0.7, 0.0≦c≦0.3, and 1.15<d<3.0, where c<b; where theremay be partial substitution of the atoms (Mg+Al+Si) by one or more otherelements T selected from the group B, Be, Zn, Ga, Fe, Ge, As and P suchthat T/(Mg+Al+Si)<0.1 and Mg is >0; where there may be partialsubstitution of the interstitial atoms M by one or more other elements Aselected from the group alkaline earth, transition metal and rare earthelements such that A/M<0.2; and where impurity minerals or compoundswhich are not integrated into the structure are not accounted for in thecomposition. Such impurity minerals or compounds may include, forexample, TiO₂ -anatase and SiO₂ -quartz.

Preferably, 0.4<a<1.4, 0.2<b<0.6, 0.0≦c≦0.2, and 1.5<d<2.5; and whereT/(Mg+Al+Si)<0.05. More preferably 0.6<a<1.3, 0.35<b<0.6, 0.0≦c≦0.1, and1.65<d<2.25; and where T/(Mg+Al+Si)<0.02. Advantageously, Mg/Ca≦100 andSi/(Mg+Ca)<1.4.

As is clear from the composition above, the interstitial cations may beK⁺ or Na⁺, as in the compounds Na₂ MgSiO₄, Na₄ Mg₂ Si₃ O₁₀, K₂ MgSiO₄,and KMg₀.5 Si₁.5 O₄, or it may be another alkali cation, such as Li⁺,Rb⁺ or Cs⁺. The alkali cations may be partially substituted by one ormore other monovalent cations, such as NH₄ ⁺ or H⁺. These materials mayalso be prepared such that a small proportion of the monovalentinterstitial cations is substituted by polyvalent cations, such asalkaline earth, transition metal and rare earth cations. Theinterstitial sites may be occupied by a mixture of any two or more ofthe aforementioned cations. However, alkali metal cations are thepreferred cations, in particular Na⁺ or K⁺.

It is believed that unreacted reagent anions which may be used in thesynthesis of magnesiosilicate compounds in accordance with theinvention, for example bicarbonate, carbonate, carboxylate, nitrate andhydroxide, are not integrated into the structures, and it is for thisreason they are not included in the empirical composition above.

As described below, compounds in accordance with the invention may bemade by aqueous routes, but we have discovered that advantageously suchcompounds having a stuffed silica polymorph-related structure may bereadily made by solid state reaction routes. Thus, also according to thepresent invention, there is provided a process for the preparation of amagnesiosilicate compound in accordance with the invention and having astuffed silica polymorph-related structure, which comprises subjecting amagnesiosilicate starting material, or a combination of magnesium oxide-and silicon oxide-containing reagents, to a solid state reaction with analkali oxide-containing reagent.

A variety of synthetic solid state reaction methods is available for usein the above process, and some of these methods in which theinterstitial cation is an alkali metal cation are described below. Thesereaction methods are preferably performed at a temperature of about1000° C. or less, more preferably at a temperature in the range of about450° C. to about 800° C. Temperatures greater than 1000° C. may be usedto achieve reaction, but the time of reaction would necessarily bereduced to prevent the formation of well crystallised, ordered materialswith a CBR>300 seconds. Advantageous to the successful synthesis ofmagnesiosilicate compounds in accordance with the invention and having astuffed silica polymorph-related structure, are reactive startingmaterials, that is components or component precursors which facilitatereaction at the above relatively low temperatures. The relatively mildreaction conditions result in the formation of less well crystallisedmaterials with substantial disordering of the framework cations, and itis this feature which is believed to lead to the relatively high CBR inthe stuffed silica polymorph-related compounds of the invention.

Preferably, the magnesiosilicate compounds in accordance with theinvention with a layered structure have their characteristic broad X-raypowder diffraction peak occurring at a d-spacing of from about 12 toabout 16 Å.

Advantageously, the magnesiosilicate compounds according to theinvention and having a layered structure are formed by an aqueous routeand in one such route according to the invention the process comprisessubjecting a magnesiosilicate starting material, or a combination ofmagnesium oxide- and silicon oxide-containing reagents, to aqueousreaction with an alkali oxide-containing reagent.

These reaction methods are preferably performed in a temperature rangeof from about 100° C. to about 300° C. in a sealed vessel, morepreferably in a temperature range of from about 150° C. to about 200° C.Temperatures greater than 300° C. and/or elevated pressures may be usedto achieve reaction, but the time of reaction would necessarily bereduced to ensure a compound in accordance with the invention isproduced.

Advantageous to the successful synthesis of magnesiosilicate compoundshaving a layered structure in accordance with the invention are reactionstarting materials, that is components or component precursors whichfacilitate reaction at the above relatively low temperatures.

To facilitate relatively mild reaction conditions for the formation ofthese magnesiosilicate compounds in accordance with the invention havingeither a stuffed silica polymorph-related structure or the layeredstructure by the processes described above, it is particularlyadvantageous to use a magnesiosilicate mineral starting material, which,by definition, contains magnesium and silicon atoms mixed on the unitcell, that is the nanometer, scale. With a high surface area and thepreferred relatively mild reaction conditions, the magnesiosilicateminerals can lead to the formation of reactive, high surface areamagnesiosilicate compounds in accordance with the invention having veryhigh CBRs.

Magnesiosilicate phyllosilicates are, in general, suitable startingmaterials for the formation of these compounds. For the purposes of thepresent invention magnesiosilicate phyllosilicates are defined asphyllosilicates having more magnesium than aluminium in theircomposition and are thereby distinguished from aluminosilicatephyllosilicates containing some magnesium.

Such magnesiosilicate phyllosilicates include the clay mineral saponite,as well as the minerals talc and chrysotile. Most preferably, thephyllosilicate is saponite or talc. While there is a significant rangein the silicon and magnesium contents of these starting materials, allare considered, to a greater or lesser extent, to be a suitable sourceof mnagnesiosilicate in the synthesis of the crystallinemagnesiosilicates having either a stuffed silica polymorph-relatedstructure or the layered structure.

One of the other advantages that mineral magnesiosilicates have asreactive starting materials is their high natural abundance andrelatively low unit cost.

Various alkali salts and hydroxides are suitable reactive startingmaterials which provide a source of the alkali cations. Most alkalisalts which decompose upon heating to 1000° C. to give alkali oxide aresuitable. Alkali halides and alkali sulfides are not suitable.

It is also possible to use reactive forms of silica, such as silica geland colloidal silica, in combination with reactive forms of magnesium,such as magnesium nitrate hexahydrate or magnesium basic carbonate, toprovide the source of magnesiosilicate for use in the above processes ofthe invention.

We have also discovered that magnesiosilicate compounds in accordancewith the invention and having the layered structure can be formed byaqueous routes from magnesiosilicate compounds having a stuffed silicapolymorph-related structure.

Thus, further according to the present invention there is provided aprocess for the preparation of a magnesiosilicate compound in accordancewith the invention and having the layered structure, which comprisestreating a magnesiosilicate compound having a stuffed silicapolymorph-related structure with aqueous solution.

The aqueous solution used in this rinsing treatment may be distilledwater or it may be, for example, water containing small or large amountsof dissolved species, such as Na⁻ -containing solution. The treatmentprocess leads to a change in composition relative to the startingmaterial, for example such that the M/Mg ratio is reduced significantlyand the Si/Mg ratio is reduced slightly.

Preferably, the magnesiosilicate compound having a stuffed silicapolymorph-related structure is in accordance with the invention.

This process may be performed at room temperature. In a preferredembodiment the magnesiosilicate compound having a stuffed silicapolymorph-related structure is dispersed in the aqueous solution, andresidual solid is separated from the supernatant liquid and dried. Thedispersing and separating steps may take no more than about minutes,preferably no less than about 10 minutes. The separated residual solidmay be dried at less than about 100° C. preferably less than about 60°C. The separating step may be, for example, by centrifuging or byfiltration.

Still further according to the present invention, there is provided theuse of a magnesiosilicate compound in accordance with the invention as awater softener and/or as a detergent builder.

Yet still further according to the present invention, there is provideda detergent composition containing a magnesiosilicate compound inaccordance with the invention and a surfactant.

Also still further according to the present invention, there is provideda moulded body comprising magnesiosilicate compound in accordance withthe invention, optionally further comprising a binder. Such a mouldedbody may be a convenient form of the magnesiosilicate compound for useas a water softener.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the magnesiosilicates having a stuffed silicapolymorph related structure and their aqueous derivatives, uses for themand processes for producing them will now be described by way of exampleonly with reference to the accompanying drawings, in which:

FIG. 1 shows polyhedral representations of high-cristobalite (SiO₂) andidealised Na₂ MgSiO₄, projected down the cubic <110> direction;

FIG. 2 shows polyhedral representations of high-tridymite (SiO₂) andidealised KMg₀.5 Si₁.5 O₄, projected down the <110> direction; and

FIGS. 3 to 6 show XRD profiles of the subject magnesiosilicate compoundsa-m prepared according to Examples 1-13 respectively. XRD data werecollected using CuKα radiation.

Peaks due to impurity minerals or reaction byproducts are indicated byasterisks.

DETAILED DESCRIPTION OF THE INVENTION

Structure and Composition of Magnesiosilicate Compounds in Accordancewith the Invention and Having a Stuffed Silica Polymorph-relatedStructure

Magnesiosilicate compounds having a stuffed silica polymorph-relatedstructure can be characterised in terms of their structure andcomposition.

The structures of the various magnesiosilicate compounds having astuffed silica polymorph-related structure are characterised mostdefinitively by X-ray powder diffraction. When well prepared thesecompounds give X-ray powder diffraction profiles which displaydiffraction peaks characteristic of the stuffed silica polymorphs.Characteristic diffraction profiles for the various magnesiosilicateshaving a stuffed silica polymorph related structure can be seen in FIGS.3 to 5 for compounds a-k of Examples 1 to 11 respectively. Thecorresponding tabulated information is given in Table 1.

Cristobalite-related sodium magnesiosilicates are characterised by thepresence of dominant X-ray powder diffraction peaks or groups of peaksoccurring simultaneously at a d-spacing of 4.30±0.15 Å and at ad-spacing of 2.64±0.22 Å. These peaks or groups of peaks are related tothe 111 and 220 X-ray powder diffraction peaks, respectively, of highcristobalite.

Cristobalite-related potassium magnesiosilicates are characterised bythe presence of a dominant X-ray powder diffraction peak or group ofpeaks occurring at a d-spacing of 2.73±0.15 Å and a weaker peak or groupof peaks at a d-spacing of 4.44±0.10 Å. These peaks or groups of peaksare related to the 220 and 111 X-ray powder diffraction peaks,respectively, of high cristobalite.

Tridymite-related potassium magnesiosilicates are characterised by thepresence of a dominant X-ray powder diffraction peak occurring at ad-spacing of 3.11±0.20 Å. This peak is related to the 202 X-ray powderdiffraction peaks of high tridymite.

The XRD profiles observed for magnesiosilicates having a stuffed silicapolymorph related structure are dependent on the choice of startingreagents and reaction conditions. They are also sometimes complicated bythe presence of unreacted starting materials, reaction byproducts suchas MgO or Na₂ SiO₃ or impurity minerals, such as quartz, calcite,dolomite and feldspar, when naturally-occurring components are used.

Both these magnesiosilicate compounds and the magnesiosilicate compoundsin accordance with the invention and having a layered structuredescribed below can be further characterised by their composition.

In the broadest embodiment the subject magnesiosilicates have acomposition range in anhydrous form given by M_(a) Mg_(b) Al_(c)Si₁₋(b+c) O_(d), (M=alkali, optionally partially substituted by H orNH₄),where 0.0<a<2.0, 0.0<b<0.7, 0.0≦c≦0.3, and 1.15<d<3.0. Also c<b.This general formula does not account for partial substitution of thetetrahedral atoms (Mg+Al+Si) by other elements T (where T=B, Be, Zn, Ga,Fe, Ge, As or P) which can occupy such positions in a tetrahedralframework structures. In the broadest embodiment T/(Mg+Al+Si)<0.1 andMg>0. Neither does this general formula account for partial substitutionof the interstitial atoms M by other elements A (where A=alkaline earth,transition metal or rare earth elements) which can occupy suchinterstitial sites in the structures. In the broadest embodimentA/M<0.2. Neither does the general formula account for impurity mineralsor compounds which are not integrated into the structure, e.g. TiO₂-anatase, SiO₂ -quartz.

In a more preferred embodiment the subject magnesiosilicates have acomposition range in anhydrous form given by M_(a) Mg_(b) Al_(c)Si₁₋(b+c) O_(d), where 0.4<a<1.4, 0.2<b<0.6, 0.0≦c≦0.2, 1.5<d<2.5, andc<b. In this more preferred embodiment T/(Mg+Al+Si)<0.05, A/M<0.2 andMg>0. Again, the general formula does not account for impurity mineralsor compounds which are not integrated into the structure, e.g. TiO₂-anatase, SiO₂ -quartz.

In the most preferred embodiment the subject magnesiosilicates have acomposition range in anhydrous form given by M_(a) Mg_(b) Al_(c)Si₁₋(b+c) O_(d), where 0.6<a<1.3, 0.35<b<0.6, 0.0≦c≦0.1, 1.65<d<2.25,and c<b. In this most preferred embodiment Ti(Mg+Al+Si)<0.02, A/M<0.2and Mg>0. Again, the general formula does not account for impurityminerals or compounds which are not integrated into the structure, e.g.TiO₂ -anatase, SiO₂ -quartz.

It is believed that unreacted reagent anions which may be used in thesynthesis of magnesiosilicate cation exchange compounds, for example,carbonate, bicarbonate, nitrate, are also not integrated into thestructures, and it is for this reason that they are not included in theempirical composition.

Composition analyses and derived formulae for magnesiosilicate compoundshaving silica polymorph-related structures and prepared according toExamples 1-11 are presented in Table 2.

                                      TABLE 1                                     __________________________________________________________________________    Relative intensities and d-spacings of characteristic diffraction peaks       of stuffed silica polymorph                                                   magnesiosilicate compounds a-k of Examples 1-11                               Example No.                                                                         d  I/I.sub.o                                                                        d   I/I.sub.o                                                                        d  I/I.sub.o                                                                        d  I/I.sub.o                                                                        d  I/I.sub.o                                                                       d  I/I.sub.o                              __________________________________________________________________________    1.    4.24                                                                             100                                                                              2.65                                                                              50 2.59                                                                             70                                                      2.    4.23                                                                             100                                                                              2.62.sub.sh                                                                       40 2.59                                                                             80                                                      3.    4.23                                                                              20                                                                              2.72                                                                              100                                                           4.    3.12                                                                             100                                                                  5.    4.26                                                                              90                                                                              2.70.sub.sh                                                                       50 2.66                                                                             100                                                                              2.58                                                                              80                                               6.    4.24                                                                             100                                                                              2.70.sub.sh                                                                       40 2.65                                                                             80 2.59                                                                              80                                               7.    4.24                                                                             100                                                                              2.69.sub.sh                                                                       50 2.64                                                                             90 2.59                                                                              80                                               8.    4.24                                                                             100                                                                              2.70.sub.sh                                                                       50 2.64                                                                             90 2.58                                                                             100                                               9.    4.24                                                                             100                                                                              2.66.sub.sh                                                                       30 2.59                                                                             80                                                      10.   4.32                                                                              50                                                                              4.24                                                                              40 2.72                                                                             50 2.64                                                                             100                                                                              2.59                                                                             60                                          11.   4.45                                                                              20                                                                              4.31                                                                              20 3.08                                                                             15 2.73                                                                             100                                                                              2.64                                                                             30                                                                              2.58                                                                             25                                     __________________________________________________________________________     sh = shoulder on main diffraction peak                                   

                                      TABLE 2                                     __________________________________________________________________________    Bulk anhydrous composition and derived formulae for subject                   magnesiosilicates (or Examples 1-11 determined by EDS                             Example 1                                                                          Example 2                                                                          Example 3                                                                          Example 4                                                                          Example 5                                                                          Example 6                                                                          Example 7                                       wt % wt % wt % wt % wt % wt % wt %                                        __________________________________________________________________________    SiO.sub.2                                                                         38.0 50.7 34.3 58.5 40.5 36.5 38.9                                        TiO.sub.2                                                                         0.0†                                                                        0.3  0.0†                                                                        0.0†                                                                        0.0†                                                                        0.5  0.0†                                 Al.sub.2 O.sub.3                                                                  4.4  5.3  3.3  0.3  2.5  3.8  4.4                                         Fe.sub.2 O.sub.3                                                                  1.1  2.3  2.4  0.0†                                                                        0.0†                                                                        0.0†                                                                        0.9                                         MgO 21.7 25.1 15.1 14.3 21.9 21.2 22.1                                        CaO 0.0†                                                                        1.1  0.5  0.0†                                                                        0.5  0.4  0.3                                         Na.sub.2 O                                                                        34.5 14.8 1.8  0.8  34.6 37.6 33.4                                        K.sub.2 O                                                                         0.3  0.4  42.6 26.1 0.0†                                                                        0.0†                                                                        0.0†                                 a   0.89 0.31 0.90 0.41 0.88 1.00 0.84                                        b   0.43 0.40 0.37 0.27 0.43 0.43 0.43                                        c   0.07 0.07 0.06 0.01 0.04 0.06 0.07                                        d*  1.98 1.72 2.05 1.93 1.99 2.04 1.96                                        __________________________________________________________________________         Example 8                                                                          Example 9                                                                          Example 10                                                                          Example 11                                                                          Example 12                                                                          Example 13                                        wt % wt % wt %  wt %  wt %  wt %                                         __________________________________________________________________________    SiO.sub.2                                                                          36.5 49.4 33.7  27.5  43.1  46.4                                         TiO.sub.2                                                                          0.0†                                                                        0.0†                                                                        0.0†                                                                         0.0†                                                                         0.0†                                                                         0.0†                                  Al.sub.2 O.sub.3                                                                   3.9  5.5  0.0†                                                                         2.0   5.6   6.0                                          Fe.sub.2 O.sub.3                                                                   0.0†                                                                        1.5  4.1   0.8   0.9   0.0†                                  MgO  22.1 29.9 26.8  14.8  28.5  26.5                                         CaO  0.3  0.4  0.6   0.0†                                                                         0.5   0.7                                          Na.sub.2 O                                                                         37.2 13.2 34.8  16.1  21.3  20.5                                         K.sub.2 O                                                                          0.0†                                                                        0.0†                                                                        0.0†                                                                         38.9  0.0†                                                                         0.0†                                  a    0.98 0.25 0.91  1.56  0.45  0.43                                         b    0.44 0.44 0.54  0.42  0.46  0.42                                         c    0.06 0.06 0.00  0.05  0.07  0.08                                         d*   2.02 1.66 1.92  2.34  1.73  1.76                                         __________________________________________________________________________     *required by charge balance  not analysed                                     †set to zero as < 2                                               

Synthesis of Magnesiosilicate Compounds in Accordance with the Inventionand Having a Stuffed Silica Polymorph-related Structure

Two general processes for the synthesis of the subject magnesiosilicatecompounds having a stuffed silica polymorph-related structure aredescribed.

1. The first process involves solid state reaction of alkali salt andmagnesium-containing phyllosilicates. The range of conditions for thesuccessful formation of these magnesiosilicate compounds by this processis dependent on the magnesium-containing phyllosilicate used.

While many alkali salts and alkali hydroxide and allmagnesium-containing phyllosilicates are suitable as starting materialsfor this process, we exemplify the process using alkali carbonate andthe phyllosilicate talc which are among the preferred startingmaterials.

In the first process the mole ratio of alkali carbonate (M₂ CO₃) to thetalc (Mg₃ Si₄ O₁₀ (OH)₂) is from 0.1 to 4.5:1. The preferred mole ratiois in the range of 2 to 3:1.

Reaction is suitably carried out at an elevated temperature atatmospheric pressure for a sufficient period of time to enableconversion to a magnesiosilicate compound having a stuffed silicapolymorph-related structure. Initially, the talc and alkali carbonateare intimately mixed then heated to between 450 and 800° C. until allthe talc has reacted. At the lower end of the temperature range thelikelihood of residual starting materials being present in the produceincreases. The preferred conditions for this process are 550 to 700° C.for a period of between 0.5 and 24 hours. The resultant solid contains amagnesiosilicate compound with a stuffed silica polymorph relatedstructure as the majority phase.

2. The second process involves solid state reaction of a reactive formof silica, a magnesium salt and an alkali salt, after the componentshave been mixed via a gel synthesis route.

The range of conditions for the successful formation of thesemagnesiosilicate compounds by this process is primarily dependent on themagnesium and alkali salts used.

While many magnesium and alkali salts and reactive forms of silica aresuitable as starting materials for this process, we exemplify theprocess using alkali nitrate, magnesium nitrate and colloidal silicawhich are among the preferred starting materials.

In the second process, the mole ratios of colloidal silica (˜SiO₂) tomagnesium nitrate (Mg(NO₃)₂) to alkali nitrate (MNO₃) are typicallyabout 1:12, but can vary substantially from this within the compositionrange described earlier. It is possible to replace the colloidal silicaby other forms of silica such as soluble alkali silicate.

Reaction takes place by dissolving the magnesium and alkali nitrate in asmall amount of water, then adding the colloidal silica to the dissolvedsalts. The reaction mixture is homogenised, then the water is evaporatedslowly, giving a gel. This gel is then further reacted at elevatedtemperature and atmospheric pressure for a sufficient period of time toenable conversion to magnesiosilicate compounds having a stuffed silicapolymorph-related structure in accordance with the invention. The gel isheated to between 450° C. and 800° C. until magnesiosilicate compoundhaving a stuffed silica polymorph related structure is observable byXRD. The preferred conditions for this process are 550° C. to 700° C.for a period of between 2 days and 6 hours.

Examples of Specific Conditions of Synthesis of MagnesiosilicateCompounds in Accordance with the Invention and Having a Stuffed SilicaPolymorph-related Structure

Examples of the specific conditions of synthesis under which thecomponents react together to give magnesiosilicates having a stuffedsilica polymorph related structure are given below.

1. 200 g of ≦25 μm talc is dispersed in 0.53 liters of water. A solutioncontaining 170 g of commercial grade Na₂ CO₃ in 0.50 liters of water isslowly added and the resultant slurry stirred vigorously for 20 minutes.This slurry is then dehydrated using a spray drier with an inlettemperature of 250° C. The spray dried reaction mixture is then heatedat 600° C. for 16 hours. The XRD profile of this material, which has acristobalite-related structure, is shown in FIG. 3 (compound a).

2. 500 g of saponite from Watheroo, Western Australia, is dispersed in2.0 liters of water A solution containing 330 g of commercial grade Na₂CO₃ in 0.75 liters of water is slowly added and the resultant slurrystirred vigorously for 20 minutes. This slurry is then dehydrated usinga spray drier with an inlet temperature of 250° C. The spray driedreaction mixture is then heated at 550° C. for 3.5 hours. The profile ofthis material which has a cristobalite-related structure is shown inFIG. 3 (compound b).

3. 5.737 g of potassium nitrate is dissolved in 5 ml of water at 50° C.This solution is added to 5 g of saponite from Watheroo, WesternAustralia, and thoroughly homogenised using a mortar and pestle thendehydrated at 100° C. The reaction mixture is then heated at 600° C. for21 hours. The XRD profile of this material which has a simple cubiccristobalite-related structure is shown in FIG. 3 (compound c).

4. 3.214 g of potassium nitrate and 4.07 g of magnesium nitratehexahydrate are dissolved in 10 ml of water at 50° C. This solution isadded to 8.98 g of Ludox AM (du Pont) colloidal silica (31.9 wt % SiO₂).A gel forms immediately upon mixing which is then dehydrated at 130° C.The dry mixture is then heated to 800° C. for 2 days. The XRD profile ofthis material which has a tridymite-related structure is shown in FIG. 3(compound d).

5. Material was prepared as for Example 1 except that a ≦20 μm talc wasused as starting material. The XRD profile of this material, which has acristobalite-related structure, is shown in FIG. 4 (compound e).

6. 200 g of partly delaminated talc, with specific surface of 18 m² g⁻¹,is dispersed in 0.6 liters of water. A solution containing 170 g ofcommercial grade Na₂ CO₃ in 0.60 liters of water is slowly added and theresultant slurry stirred vigorously for minutes. This slurry is thendehydrated using a spray drier with an inlet temperature of 275° C. Thespray dried reaction mixture is then heated at 550° C. for 16 hours. TheXRD profile of this material, which has a cristobalite-relatedstructure, is shown in FIG. 4 (compound f).

7. 100 g of partly delaminated talc, with specific surface of 18 m² g⁻¹,is dispersed in 0.3 liters of water. A solution containing 68 g ofcommercial grade Na₂ CO₃ in 0.24 liters of water is slowly added and theresultant slurry stirred vigorously for minutes. This slurry is thendehydrated using a spray drier with an inlet temperature of 275° C. Thespray dried reaction mixture is then heated at 550° C. for 16 hours. TheXRD profile of this material, which has a cristobalite-relatedstructure, is shown in FIG. 4 (compound g).

8. 120 g of ball milled talc, with specific surface of 45 m² g⁻¹, isdispersed in 0.36 liters of water. A solution containing 102 g ofcommercial grade Na₂ CO₃ in 0.36 liters of water is slowly added and theresultant slurry stirred vigorously for 20 minutes. This slurry is thendehydrated using a spray drier with an inlet temperature of 275° C. Thespray dried reaction mixture is then heated at 550° C. for 16 hours. TheXRD) profile of this material, which has a cristobalite-relatedstructure, is shown in FIG. 4 (compound h).

9. 200 g of ≦25 μm talc is dispersed in 0.5 liters of water. A solutioncontaining 85 g of commercial grade Na₂ CO₃ in 0.25 liters of water isslowly added and the resultant slurry stirred vigorously for 20 minutes.This slurry is then dehydrated using a spray drier with an inlettemperature of 250° C. The spray dried reaction mixture is then heatedat 600° C. for 16 hours. The XRD profile of the reaction productcontains a mixture of cristobalite-related structures and a smallquantity of unreacted talc, shown in FIG. 5 (compound i)

10. 0.5 g of chrysotile, with nominal composition Mg₃ Si₂ O₅ (OH)₄, isreacted with 0.6 g of sodium carbonate by thoroughly grinding the solidstogether then reacting the mixture at 500° C. for 16 hours. The reactionproduct is then reground and reacted at 650° for 4 days, then at 800° C.for a further 4 days. The XRD profile of the reaction product whichshows a cristobalite-related structure as the main phase, as well assome MgO, is shown in FIG. 5 (compound j).

11. 100 g of partly delaminated talc, with specific surface of 18 m²g⁻¹, is dispersed in 0.3 liters of water. A solution containing 42.5 gof commercial grade Na₂ CO₃ and 66.2 g of commerical grade K₂ CO₃.1.5H₂O in 0.24 liters of water is slowly added and the resultant slurrystirred vigorously for 20 minutes. This slurry is then dehydrated usinga spray drier with an inlet temperature of 275° C. The spray driedreaction mixture is then hated at 500° C. for 16 hours. The XRD profileof this material, which has a cristobalite-related structure, is shownin FIG. 5 (compound k).

Structure and Composition of Magnesiosilicate Compounds in Accordancewith the Invention Having the Layered Structure

The structures of these magnesiosilicate compounds having a layeredstructure are characterised most definitively by X-ray powderdiffraction. When well prepared they give X-ray powder diffractionprofiles which display a characteristic broad diffraction peakcorresponding to a d-spacing of between 11 and 17 Å. Examples ofcharacteristic diffraction profiles for these compounds can be seen inFIG. 6 for compounds 1 and m of Examples 12 and 13 respectively.Preferably, the characteristic broad diffraction peak corresponds to ad-spacing of between 12 and 16 Å.

The compositions of these magnesiosilicate compounds in accordance withthe invention having the layered structure are as described above forthe magnesiosilicate compounds having a stuffed silica polymorph-relatedstructure.

Composition analyses and derived formulae for magnesiosilicate compoundsl and m having the layered structure and prepared according to Example12 and 13 respectively are presented in Table 2.

Synthesis of Magnesiosilicate Compounds in Accordance with the Inventionand Having the Layered Structure

Two general processes for the synthesis of the subject magnesiosilicatecompounds having the layered structure are described.

1. The first process comprises treating a magnesiosilicate compound witha stuffed silica polymorph structure with water, whereby the startingcompound is dispersed in water for a time, the remaining solid thenbeing separated by centrifuge or by filtration from the supernatantliquid then dried.

The preferred duration of this treatment is less than about 20 minutes,and preferably less than about 10 minutes, with the drying of theresultant solid product taking place at less than about 100° C., andpreferably less than about 60° C.

The water used in rinsing may be distilled water or it may be watercontaining small or large amounts of dissolved species, such as an Na⁺-containing solution. The rinsing process leads to a change incomposition relative to the starting material such that the Na/Mg ratiois reduced significantly and the Si/Mg ratio is reduced slightly.However, the resulting composition remains within the broad compositiondescribed above.

2. The second process comprises subjecting a magnesiosilicate materialstarting material, or a combination of magnesium oxide- and siliconoxide-containing reagents, to aqueous reaction with an alkalioxide-containing reagent.

The reaction is performed at a temperature between 100 and 300° C. in asealed vessel, and preferably between 150 and 200° C.

The alkali oxide-containing reagent preferably decomposes in air at atemperature below about 1000° C. to give alkali oxide, and is morepreferably selected from one or more of the group bicarbonate,carbonate, carboxylate, nitrate and hydroxide.

A preferred embodiment of the process is where the magnesiosilicatestarting material comprises a phyllosilicate mineral, and morepreferably where the phyllosilicate mineral is talc or saponite.

Examples of Specific Conditions of Synthesis of MagnesiosilicateCompounds in Accordance with the Invention and Having the LayeredStructure

An example of the first process for the synthesis of themagnesiosilicate compounds having the layered structure is given below.

EXAMPLE 12

1.0 g of the material prepared according to Example 6 is dispersed in 40ml of distilled water and then centrifuged to separate the solid fromthe supernatant liquid, the full procedure taking about 10 minutes. Thesolid is then dried at 40° C., yielding 0.82 g of white powder. The XRDprofile of the magnesiosilicate compound, which shows a dominant, broadpeak at a d-spacing of ˜12.5 Å and remnant peaks due to the stuffedsilica polymorph related structure of the starting material, is shown inFIG. 6 (compound l).

An example of the second process for the synthesis of themagnesiosilicate compounds having the layered structure is given below.

EXAMPLE 13

1.483 g of NaOH is dissolved in 3 ml of water followed by the additionof 3.703 g of sodium silicate solution. The combined solution is thenadded to 1.264 g of talc in a mortar and pestle and thoroughly ground,producing a thick slurry. This slurry is then placed in a teflon-linedsealed pressure vessel and heated at 185-190° C. for 1 week. Theresultant solid is then removed from the vessel and rinsed with ˜50 mlof water. The solid is then dried at 40° C. The XRD profile of themagnesiosilicate compound, which shows a dominant, broad peak at ad-spacing of ˜15.0 Å and remnant sharp peaks due to unreacted chloritefrom the starting material, is shown in FIG. 6 (compound m).

Preparation of a Monolithic Body

For some applications of the magnesiosilicate compounds in accordancewith the invention, particularly for use as a water softener, it may bedesirable to prepare a monolithic body. This can be achieved for thosecompound formed by the solid state reaction route by pressing the dryreaction mixture into its desired form prior to the solid statereaction. A robust, porous body can be produced in this manner. A bindermay be included to further enhance the robustness of the body.

One Embodiment of Such a Process is Described in Example 14

EXAMPLE 14

1 g of spray dried reaction mixture described in Example 1 is pressedinto a monolithic form using a uniaxial press at a pressure of 2000kgcm⁻² for 3 minutes. The resultant pellet is then reacted at 650° C.for 16 hours, producing a robust pellet with 52% of theoretical density.

Calcium Binding Capacity

For the purposes of the present invention two different methods wereused to determine calcium binding capacity (CBC). Calcium bindingcapacity is measured as milligrams of CaO taken up per gram of themagnesiosilicate compound at room temperature.

Method A

To characterise the magnesiosilicate compounds in accordance with theirproposed utility as water softeners or detergent builders, a methodsimilar to that described in GB 1 473 201 (Henkel) and EP 0 384 070 A2(Unilever) was used. In this test 0.1 g of test compound was dispersedin 100 ml of 10 an aqueous solution containing 202 ppm of Ca²⁺, andwhere necessary, adjusted to a pH of with dilute NaOH. The suspensionwas stirred at 20° C. for 15 minutes, then centrifuged to remove thesolid. The aqueous solution was then tested for residual Ca²⁺ using acalcium-selective electrode.

Various examples of the subject magnesiosilicate compounds and, forcomparison, other commercially produced detergent builders were tested.The results of these tests are given in Table 3 below. All of themagnesiosilicate compounds of Examples 1 to 14 above have a CBC ofgreater than 10 mg CaO at room temperature.

                  TABLE 3                                                         ______________________________________                                        Residual Ca.sup.2+  concentration and derived CBC using Method A*                                           Derived CBC                                     Material          Ca.sup.2+  conc. (ppm)                                                                    (mg CaO/g)                                      ______________________________________                                        Example 1         133.6        96.0                                           Example 5         133.6        96.0                                           Example 6         81.3        169.2                                           Example 7         96.3        145.4                                           Example 8         84.0        165.4                                           Zeolite P (EP 0 565 364 A1)                                                                     81.3        169.2                                           Zeolite 4A (Wessalith P, Degussa)                                                               92.8        153.1                                           Zeolite 4A (Valfor, PQ Corp.)                                                                   78.0        173.9                                           SKS-6 (Hoechst)   66.7        186.9                                           ______________________________________                                         *Initial Ca.sup.2+  concentration of 202.2 ppm, equivalent to 282.9 mg        CaO/g at loading of 0.1 g per 100 ml.                                    

Method B

Calcium binding capacities were also compared in the presence ofbackground 0.01 M Na⁺ in a manner similar to the method described in EP0 384 070 A2 (Unilever) for the purpose of more closely simulating awash liquor environment. In this test 0.1 g of compound was dispersed in100 ml of an 0.01 M NaCl solution containing 202 ppm of Ca²⁺, and wherenecessary, adjusted to a pH of 10 with dilute NaOH. The suspension wasstirred at 20° C. for 15 minutes, then centriged to remove the solid.The aqueous solution was then tested for residual Ca²⁺ using acalcium-selective electrode.

Various examples of the subject magnesiosilicate compounds and, forcomparison, other commercially produced detergent builders were tested.The results of these tests are given in Table 4 below.

                  TABLE 4                                                         ______________________________________                                        Residual Ca.sup.2+  concentration and derived CBC using Method B*                                           Derived CBC                                     Material          Ca.sup.2+  conc. (ppm)                                                                    (mg CaO/g)                                      ______________________________________                                        Example 1         131.2        99.2                                           Example 5         121.1       113.4                                           Example 6         65.9        190.5                                           Example 7         102.6       136.6                                           Example 8         73.8        179.5                                           Zeolite P (EP 0 565 364 A1)                                                                     91.7        154.4                                           Zeolite 4A (Wessalith P, Degussa)                                                               86.3        162.0                                           Zeolite 4A (Valfor, PQ Corp.)                                                                   100.0       142.8                                           SKS-6 (Hoechst)   83.4        163.5                                           ______________________________________                                         *Initial Ca.sup.2+  concentration of 202.2 ppm, equivalent to 282.9 mg        CaO/g at loading of 0.1 g per 100 ml.                                    

Magnesium Binding Capacity

Magnesium binding capacity is measured as milligrams of MgO taken up pergram of the magnesiosilicate compound at room temperature.

Method C

To characterise the magnesiosilicate compounds further in accordancewith their proposed utility as water softeners or detergent builders, amethod C similar to Method A described above was used to measuremagnesium binding capacity (MBC). In this test 0.1 g of test compoundwas dispersed in 100 ml of an aqueous solution containing 200 ppm ofMg²⁺ and, where necessary, adjusted to a pH of 10 with dilute NaOH. Thesuspension was stirred at 20° C. for 15 minutes, then centrifuged toremove the solid. The aqueous solution was then tested for residual Mg²⁺using atomic absorption spectroscopy.

Various examples of the subject magnesiosilicate compounds and, forcomparison, other commercially produced detergent builders were tested.The results of these tests are given in Table 5 below. All of themagnesiosilicate compounds of Examples 1 to 14 above have an MCB ofgreater than 10 mg MgO at room temperature.

                  TABLE 5                                                         ______________________________________                                        Residual Mg.sup.2+  concentration and derived MBC using Method C                                            Derived MBC                                     Material          Mg.sup.2+  conc. (ppm)                                                                    (mg MgO/g)                                      ______________________________________                                        Example 1         168          53.1                                           Example 5         167          54.7                                           Example 6         112         145.9                                           Example 7         102         162.5                                           Example 8          82         195.7                                           Zeolite P (EP 0 565 364 A1)                                                                     198          3.3                                            Zeolite 4A (Wessalith P, Degussa)                                                               174          43.1                                           Zeolite 4A (Valfor, PQ Corp.)                                                                   178          36.5                                           SKS-6 (Hoechst)    77         204.0                                           ______________________________________                                         *Initial Mg.sup.2+ concentration of 200 ppm, equivalent to 331.7 mg MgO/g     at loading of 0.1 g per 100 ml.                                          

Calcium Binding Rate (CBR)

Calcium binding rate is measured as the time taken to remove half of theCa²⁺ from approximately a 100 ppm Ca²⁻ solution at room temperature at aloading of 3 g of the magnesiosilicate compound per liter.

Method D

The subject magnesiosilicate compound are further characterised in termsof their calcium binding rate (CBR) in accordance with their utility aswater softeners or detergent builders To quantify the rate at which Ca²⁺is removed from solution, using method D, 0.15 g of test compound isdispersed in ˜1 ml of water which is then injected into 50 ml of stirredsolution containing 0.01 M NaCl, 0.1 M KCl and ˜100 ppm of Ca²⁻concentration of the stirred solution is measured as a function of timeusing a calcium selective electrode.

Various examples of the subject magnesiosilicate compounds and, forcomparison, other commerically produced detergent builders were tested.The results of these test are given in table (6). All of themagnesiosilicate compounds of Examples 1 to 13 above have a CBR of lessthan 300 seconds at room temperature.

                  TABLE 6                                                         ______________________________________                                        Calcium binding rate according to Method D.                                   Material            Time (seconds)†                                    ______________________________________                                        Example 1           5.0                                                       Example 2           270                                                       Example 5           4.5                                                       Example 6           1.5                                                       Example 7           10.0                                                      Example 8           2.5                                                       Example 11          12.0                                                      Example 12          9.5                                                       Zeolite P (EP 0 565 364 A1)                                                                       14.5                                                      Zeolite 4A (Wessalith P, Degussa)                                                                 11.5                                                      Zeolite 4A (Valfor, PQ Corp.)                                                                     11.5                                                      SKS-6* (Hoechst)    250                                                       ______________________________________                                         † time to remove half of the Ca.sup.2+  from solution.                 *material added dry due to inability to disperse in 1 ml of water        

Oil Absorption (OA)

Oil absorption was determined by the ASTM spatula rub-out method D281 asalso used in EP 0 565 364 A1. This test is based on the principle ofmixing linseed oil with the particulate material by rubbing with aspatula on a smooth surface until a stiff putty-like paste is formedwhich will not break or separate when it is cut with a spatula. The OilAbsorption (OA) is expressed in grams of oil per 100 g of dry material.

Various examples of the subject magnesiosilicate compounds and, forcomparison, other commercially produced detergent builders were tested.The results of these tests are given in Table 7 below.

                  TABLE 7                                                         ______________________________________                                        Oil Absorption results using ASTM method D281.                                Sample   OA       Sample             OA                                       ______________________________________                                        Example 1                                                                              60-92    Zeolite P (EP 0 565 364 A1)                                                                      63-77                                    Example 5                                                                              102      Zeolite 4A (Valfor, PQ Corp.)                                                                    36-43                                    Example 6                                                                              107-113  Zeolite 4A (Wessalith P, Degussa)                                                                60                                       Example 7                                                                              107      SKS-6 (Hoechst)    95                                       Example 8                                                                               77                                                                  Example 11                                                                             154                                                                  ______________________________________                                    

Use in Detergent Formulation

One example of the subject magnesiosilicate compounds was tested for itsutility as a detergent builder in comparison with the commercially usedmaterials, Zeolite 4A and sodium tripolyphosphate (STPP). The threeformulations tested are given in Table 8 below.

Other formulations incorporating the subject magnesiosilicate compoundsmay be adopted for detergent compositions as will be readily understoodby those skilled in the detergency art. By way of example only, wedirect reference to the discussion on detergent compositions inEP-A-0384070 and its United States equivalent (which are incorporatedherein by reference) which applies mutatis mutandis to detergentcompositions incorporating the subject magnesiosilicate compounds.

                  TABLE 8                                                         ______________________________________                                        Laundry detergent formulations used in comparative swatch tests.                       Formulation A                                                                          Formulation B                                                                             Formulation C                                            STPP built                                                                             Zeolite 4A built                                                                          Ex. 1 built                                     ______________________________________                                        Sodium tripoly-                                                                          15.0%                                                              phosphate                                                                     Zeolite 4A            18.0%                                                   Magnesiosilicate                  18.0%                                       Ex. 1                                                                         Dense soda ash                                                                           25.0%      24.0%        5.3%                                       Sodium sulphate                                                                          31.4%      29.4%       48.1%                                       Coconut     2.5%       2.5%        2.5%                                       diethanalamide 1:1                                                            Sodium dodecyl                                                                           15.0%      15.0%       15.0%                                       benzene suphonate                                                             Sodium metasilicate                                                                      10.0%      10.0%       10.0%                                       (DMS)       0.1%       0.1%        0.1%                                       bis(triazinylamino)                                                           stilbene di sulphonic                                                         acid der.                                                                     ______________________________________                                    

Comparative Laundry Swatch Test Results

The comparative tests described below used a FOM 71 LAB front loading 7kg capacity washer-extractor. The three formulations as listed in Table8 were dosed at 8 g/L with liters of water per wash.

The two swatches used were EMPA 105, which contained five regions(white, carbon black/oil, blood, chocolate & milk, red wine) and whitecotton.

Each of the two swatches was washed separately with each of the threeformulations A to C under four sets of conditions as follows:

1. Soft water (17 mg/L CaCO₃) at 20° C.

2. Hard water (135 mg/L CaCO₃) at 20° C.

3. Soft water (17 mg/L CaCO₃) at 60° C.

4. Hard water (135 mg/L CaCO₃) at 60° C.

Comparative results are listed in Tables 9 to 12 below giving visualestimation of the colour of each region on each swatch and a ranking ofperformance.

                                      TABLE 9                                     __________________________________________________________________________    Soft water (17 mg/L CaCO.sub.3) at 20° C.                              EMPA 105                           White Cotton                               EMPA 105    Carbon     Chocolate   WHITE                                      Swatch No.                                                                           White                                                                              Black/Oil                                                                          Blood & Milk                                                                              Red Wine                                                                            Swatch No.                                 __________________________________________________________________________    Formulation A                                                                        1    = 1  1     1 pale fawn/                                                                        1     Formulation A                                                                        1                                          white                                                                              grey pale yellow                                                                         brown pale fawn    white                               Formulation B                                                                        = 2  = 1  3 deeper                                                                            2 pale fawn/                                                                        2     Formulation B                                                                        2 slightly                                 pale cream                                                                         grey yellow                                                                              brown pale fawn    duller white                        Formulation C                                                                        = 2  2    2     3 darker                                                                            3 slightly                                                                          Formulation C                                                                        3 duller                                   pale cream                                                                         mid grey                                                                           yellow                                                                              brown darker fawn  white                               Unwashed                                                                             Dull white                                                                         Pantone                                                                            Pantone                                                                             Pantone                                                                             Pantone                                                                             Unwashed                                                                             white                               blank       423U 4635U 728U  4755U blank                                                  slate grey                                                                         dark brown                                                                          coffee brown                                                                        fawn brown                                       __________________________________________________________________________

                                      TABLE 10                                    __________________________________________________________________________    Hard water (135 mg/L CaCO.sub.3) at 20° C.                             EMPA 105                            White Cotton                              EMPA 105    Carbon     Chocolate    WHITE                                     Swatch No.                                                                           White                                                                              Black/Oil                                                                          Blood & Milk                                                                              Red Wine                                                                             Swatch No.                                __________________________________________________________________________    Formulation A                                                                        1    1    1     1 pale                                                                              1      Formulation A                                                                        3                                         white                                                                              pale grey                                                                          pale cream                                                                          fawn/brown                                                                          pale fawn     dull white                         Formulation B                                                                        3    3    3     2 chocolate                                                                         2      Formulation B                                                                        1                                         off white                                                                          pale grey                                                                          deep cream                                                                          brown pale fawn     white                              Formulation C                                                                        2    2    2     3 chocolate                                                                         3      Formulation C                                                                        2                                         off white                                                                          pale grey                                                                          dark cream                                                                          brown darker fawn   white                              Unwashed                                                                             Dull white                                                                         Pantone                                                                            Pantone                                                                             Pantone                                                                             Pantone                                                                              Unwashed                                                                             white                              blank       423U 4635U 728U  4755U  blank                                                 slate grey                                                                         dark brown                                                                          coffee brown                                                                        fawn brown                                       __________________________________________________________________________

                                      TABLE 11                                    __________________________________________________________________________    Soft water (17 mg/L CaCO.sub.3) at 60° C.                              EMPA 105                            White Cotton                              EMPA 105    Carbon      Chocolate   WHITE                                     Swatch No.                                                                           White                                                                              Black/Oil                                                                           Blood & Milk                                                                              Red Wine                                                                            Swatch No.                                __________________________________________________________________________    Formulation A                                                                        1    1     2     2     1     Formulation A                                                                        1 slightly                                white                                                                              pale grey                                                                           pale fawn                                                                           red brown                                                                           pale fawn    off white                          Formulation B                                                                        3    2     3     1     2     Formulation B                                                                        = 2                                       cream                                                                              grey  fawn  pale brown                                                                          sandy        off white                          Formulation C                                                                        2    3     1     3 darker                                                                            3     Formulation C                                                                        = 2                                       cream                                                                              darker grey                                                                         pale fawn                                                                           brown brown        off white                          Unwashed                                                                             Dull white                                                                         Pantone                                                                             Pantone                                                                             Pantone                                                                             Pantone                                                                             Unwashed                                                                             white                              blank       423U  4635U 728U  4755U blank                                                 slate grey                                                                          dark brown                                                                          coffee brown                                                                        fawn brown                                      __________________________________________________________________________

                                      TABLE 12                                    __________________________________________________________________________    Hard water (135 mg/L CaCO.sub.3) at 60° C.                             EMPA 105                           White Cotton                               EMPA 105    Carbon     Chocolate   WHITE                                      Swatch No.                                                                           White                                                                              Black/Oil                                                                          Blood & Milk                                                                              Red Wine                                                                            Swatch No.                                 __________________________________________________________________________    Formulation A                                                                        = 1  1    1     1     1     Formulation A                                                                        = 1                                        white                                                                              pale grey                                                                          pale fawn                                                                           pink ochre                                                                          pale fawn    white                               Formulation B                                                                        = 1  2    2     2     2     Formulation B                                                                        2                                          white                                                                              pale grey                                                                          pale fawn                                                                           pink ochre                                                                          sandy        off white                           Formulation C                                                                        2    3    3     3 chocolate                                                                         3     Formulation C                                                                        = 1                                        cream                                                                              dark grey                                                                          dark khaki                                                                          brown dark sand    white                               Unwashed                                                                             Dull white                                                                         Pantone                                                                            Pantone                                                                             Pantone                                                                             Pantone                                                                             Unwashed                                                                             white                               blank       423U 4635U 728U  4755U blank                                                  slate grey                                                                         dark brown                                                                          coffee brown                                                                        fawn brown                                       __________________________________________________________________________

These comparative results demonstrate that the subject magnesiosilicatescompare well with Na zeolite A and therefore have utility asphosphate-free detergent builders.

Those skilled in the art will appreciate that the invention describedherein is susceptible to variations and modifications other than thosespecifically described. It is to be understood that the inventionincludes all such variations and modifications which fall within itsspirit and scope. The invention also includes all of the steps,features, compositions and compounds referred to or indicated in thisspecification, individually or collectively, and any and allcombinations of any two or more of said steps or features.

We claim:
 1. A magnesiosilicate compound having a calcium bindingcapacity (CBC) of at least mg CaO per gram at room temperature, amagnesium binding capacity (MBC) of at least mg MgO per gram at roomtemperature, a calcium binding rate (CBR) of no more than 300 seconds atroom temperature, being the time taken to remove half of the Ca²⁺ from a˜100 ppm Ca²⁺ solution at a loading of 3 g per liter, and having astuffed silica polymorph-related structure.
 2. A magnesiosilicatecompound according to claim 1 which has a composition in anhydrous formgiven by M_(a) Mg_(b) Al_(c) Si₁₋(b+c)O_(d), where M=alkali, optionallypartially substituted by H or NH₄ ; where 0.0<a<2.0, 0.0<b<0.7,0.0≦c≦0.3, and 1.15<d<3.0; where c<b; where there may be partialsubstitution of the atoms (Mg+Al+Si) by one or more other elements Tselected from the group B, Be, Zn, Ga, Fe, Ge, As and P such thatT/(Mg+Al+Si)<0.1 and Mg>0; where there may be partial substitution ofthe interstitial atoms M by one or more other elements A selected fromthe group alkaline earth, transition metal and rare earth elements suchthat A/M<0.2; and where impurity minerals or compounds which are notintegrated into the structure are not accounted for in the composition.3. A magnesiosilicate compound according to claim 2 where 0.4<a<1.4,0.2<b<0.6, 0.0≦c≦0.2, and 1.5<d<2.5; and where T/(Mg+Al+Si)<0.05.
 4. Amagnesiosilicate compound according to claim 3 where 0.6<a<1.3,0.35<b<0.6, 0.0≦c≦0.1, and 1.65<d<2.25; and where T/(Mg+Al+Si)<0.02. 5.A magnesiosilicate compound according to claim 2 where Mg/Ca ≦100 andSi/(Mg+Ca)<1.4.
 6. A magnesiosilicate compound according to claim 1wherein M is selected from one or both of K and Na.
 7. Amagnesiosilicate compound according to claim 1 which has a stuffedsilica polymorph-related structure, where the dominant X-ray powderdiffraction peaks or groups of peaks occur simultaneously at a d-spacingof 4.30±0.15 Å and at a d-spacing of 2.64±0.22 Å.
 8. A magnesiosilicatecompound according to claim 1 which has a stuffed silicapolymorph-related structure, where the dominant X-ray powder diffractionpeak or group of peaks occurs at a d-spacing of 2.73±0.15 Å and a weakerpeak or group of peaks at a d-spacing of 4.44±0.10 Å.
 9. Amagnesiosilicate compound according to claim 1 which has a stuffedsilica polymorph-related structure, where the dominant X-ray powderdiffraction peak occurs at a d-spacing of 3.11±0.20 Å.
 10. Amagnesiosilicate compound according to claim 1 which has a CBC of atleast 50 mg CaO per gram at room temperature.
 11. A magnesiosilicatecompound according to claim 1 which has an MBC of at least 40 mg MgO pergram at room temperature.
 12. A magnesiosilicate compound according toclaim 1 which has a CBR of no more than 100 seconds at room temperature.13. A magnesiosilicate compound according to claim 1 which has an oiladsorption (OA) of at least 50 g oil per 100 g of anhydrous material.14. A magnesiosilicate compound according to claim 1 which is preparedusing magnesiosilicate mineral starting material.
 15. A magnesiosilicatecompound according to claim 1 which has a CBC of at least 150 mg CaO pergram at room temperature.
 16. A magnesiosilicate compound according toclaim 1 which has an MBC of at least 140 mg MgO per gram at roomtemperature.
 17. A magnesiosilicate compound according to claim 1 whichhas a CBR of no more then 10 seconds at room temperature.
 18. Amagnesiosilicate compound according to claim 1 which has an oiladsorption (OA) of at least 100 g oil per 100 g of anhydrous material.19. A process for the preparation of a magnesiosilicate compoundaccording to claim 1 and having a stuffed silica polymorph-relatedstructure, which comprises subjecting a magnesiosilicate startingmaterial, or a combination of magnesium oxide- and siliconoxide-containing reagents, to a solid state reaction with an alkalioxide- containing reagent.
 20. A process according to claim 19 in whichthe reaction is performed at a temperature of about 1000° C. or less.21. A process according to claim 20 in which the reaction is performedin a temperature range of about 450 to about 800° C.
 22. A processaccording to claim 19 wherein the alkali oxide-containing reagentdecomposes in air at a temperature below about 1000° C. to give alkalioxide.
 23. A process according to claim 22 wherein the alkali oxide-containing reagent is selected from one or more of the groupbicarbonate, carbonate, carboxylate, nitrate and hydroxide.
 24. Aprocess according to claim 19 wherein the alkali oxide-containingreagent contains one or both K and Na.
 25. A process according to claim19 wherein the magnesiosilicate starting material comprises aphyllosilicate mineral.
 26. A process according to claim 25 wherein thephyllosilicate mineral is selected from one or both of talc andsaponite.
 27. A magnesiosilicate compound according to claim 1 useful asa water softener.
 28. A magnesiosilicate compound according to claim 1useful as a detergent builder.
 29. A detergent composition containing amagnesiosilicate compound according to claim 1 and a surfactant.
 30. Amoulded body comprising magnesiosilicate compound according to claim 1,optionally further comprising a binder.
 31. A process for thepreparation of a magnesiosilicate compound having a layered structurewith a characteristic broad X-ray powder diffraction peak occurring at ad-spacing of between 11 and 17 Å, which comprises treating amagnesiosilicate compound having a calcium binding capacity (CBC) of atleast mg CaO per gram at room temperature, a magnesium binding capacity(MBC) of at least 10 mg MgO per gram at room temperature, a calciumbinding rate (CBR) of no more than 300 seconds at room temperature,being the time taken to remove half of the Ca²⁺ from a ˜100 ppm Ca²⁺solution at a loading of 3 g per liter, and having a stuffed silicapolymorph-related structure with aqueous solution.
 32. A processaccording to claim 31 wherein the magnesiosilicate compound having astuffed silica polymorph-related structure has a CBC of at least 20 mgCaO per gram at room temperature, an MBC of at least 15 mg MgO per gramat room temperature, and a CBR of no more then 200 seconds at roomtemperature.
 33. A process according to claim 31 in which themagnesiosilicate compound having a stuffed silica polymorph-relatedstructure is dispersed in the aqueous solution, and wherein residualsolid is separated from supernatant liquid and dried.
 34. A processaccording to claim 33 wherein the dispersing and separating steps takeno more than about 20 minutes.
 35. A process according to claim 33wherein the separated residual solid is dried at less than about 100° C.36. A process according to claim 33 wherein the dispersing andseparating steps take less than about 10 minutes.
 37. A processaccording to claim 33 wherein the separated residual solid is dried atless than about 60° C.